I'm pretty sure James McBride, who can play jazz saxophone in any idiom he wants, won't mind if I crib from the great blues singer Big Joe Turner in describing McBride's new novel, "The Good Lord Bird," as rolling "like a big wheel in a Georgia cotton field." This historical epic about a young slave's perilous, life-changing encounters with the radical abolitionist John Brown doesn't just roll, though. It dips, pitches, ebbs and surges like a vast river swollen with wit, whoppers and wisdom.

"The Good Lord Bird" is presented as the colloquial memoir of one Henry Shackleford, who is 10 years old and a slave living in a town straddling the borders of Kansas and Missouri territories of 1856 -- a time and place that was a volatile flashpoint in the bloody battle over slavery. And who should happen to wander into the barber's chair of Henry's father one day but a "stooped, skinny feller, fresh off the prairie, smelling like buffalo dung, with a nervous twitch in his jaw and a chin full of ragged whiskers."

This is John Brown, the most-wanted man in Kansas, who's been leading a ragged, misbegotten army through the territories on a violent mission to set enslaved African-

Americans free. Through a cacophony of gunfire and bloodshed, Brown flees with Henry in tow, convinced he is carrying the "tragic octoroon daughter" of the boy's soon-to-be-dead Pa. The father's protestation that "Henry ain't a . . . " is processed in Brown's tempestuous brain as "Henrietta."

And so, for the rest of this account, Henry is taken by almost everybody he meets for a girl in pantaloons and bonnets, and he won't try to talk anybody out of it, least of all Old Man Brown. "It didn't matter to him whether it was really true or not," Henry says. "He just changed the truth till it fit him. He was a real white man."

That assessment lets readers know they're not going to get standard-issue hagiography from McBride, author of the acclaimed memoir "The Color of Water." McBride's portrait of Brown as Scripture-quoting zealot with a few screws loose is tempered with melancholy awe for his visionary courage. He applies similarly humane, but gimlet-eyed rigor to his depiction of Frederick Douglass.

This rousing adventure sustains both its ironic intelligence and its fierce momentum right on through Brown's ill-fated 1859 raid on Harpers Ferry. "The Good Lord Bird" is the latest and most effervescent exemplar of works by African-American authors who have retrieved imaginative autonomy over their past and used their discoveries to illuminate what James Baldwin once characterized as "the common history . . . Ours."